Juju
Juju is an open-source application modeling and orchestration tool that simplifies the deployment, scaling, and management of applications across various cloud platforms and bare-metal servers. It uses a model-driven approach where applications are defined as 'charms'—reusable, shareable packages that encapsulate the knowledge of how to deploy and operate software. This enables developers and operators to automate complex multi-service deployments with minimal manual intervention.
Developers should learn Juju when working on cloud-native applications, microservices architectures, or DevOps automation that requires consistent deployment across hybrid or multi-cloud environments. It is particularly useful for scenarios involving complex application stacks (e.g., Kubernetes clusters, big data pipelines, or web applications with databases) where automation, repeatability, and scalability are critical. Juju reduces operational overhead by abstracting infrastructure details and providing a declarative way to manage application lifecycles.